Symbolic jacobian of an arm
Hi all,
I've a 7 DOF arm described in .xacro format and I would like to extrapolate its jacobian in symbolic form (not numerical angle values in the matrix ).
I tried to use KDL for this scope, and I was able to obtain the jacobian of this arm but in a numerical form. That is, during a gazebo simulation, I could read the values of each angles, insert them in the jacobian matrix with a specific kdl command, and obtain the jacobian matrix on every gazebo step time.
That's ok, but if I have another target in which I need the symbolic for of this jacobian from which extrapolate other matrix (inertial, coriolis ecc..), I'm not able to do this. (For example if I want to control my arm in a particular way in which I need the dynamic expression of the system).
Has anyone every have this problem? Is there a method with kdl or another software that I can use?
Thank you!
Asked by gabri89 on 2016-06-05 05:52:15 UTC
Answers
If you need the symbolic Jacobian of your robot you should calculate it in symbolic form using Matlab for example. It allows symbolic calculation as exemplified in this page. Moreover, the Matlab Robotic Toolbox has a C code generator useful to directly output the calculated symbolic quantities in C format.
On the other hand, KDL library allows you to numerically compute the matrices of the robot dynamic model (e.g. Inertia, Coriolis, Gravity) starting from robot state (joint positions, velocities). You can find the detailed implementation here.
Hope this can help.
Asked by mrslvgg on 2016-06-08 07:07:10 UTC
Comments
Is it possible to use KDL library in each step in gazebo for example in designing controller?
Asked by abbas on 2016-07-31 04:58:07 UTC
Yes, you can write a plugin that uses KDL.
Asked by nkoenig on 2016-08-01 10:17:31 UTC
I would be happy to contribute to the writing of the KDL plugin
Asked by mrslvgg on 2016-08-14 07:09:52 UTC
MarioSelvaggio, I really appreciate your intention, may I have your email, this is mine: nabafa_raiehe@yahoo.com
Asked by abbas on 2016-08-24 10:38:48 UTC
Sure. My email address is: mar.selvaggio@gmail.com
Asked by mrslvgg on 2016-08-26 00:03:10 UTC
Comments
Hi Did you resolved your problem? I have almost the same problem as you I want to use Coriolis vector in my controller, do you have any suggestion for me? I have read many things in last days and I just got confused. I have tried to use DART library but till now it was not helpful, I really appreciate if you can help me. Thanks.
Asked by abbas on 2016-07-31 05:18:54 UTC